Issue#87 Enable Users to Customize Email Body Modification

[Jennikon]

Description

Add possibility for user to provide his custom email body with parametrized dq stats.
For now only string custom email body is available.
User can import in custom body following statistics:
'product_id'
'table_name'
'input_count'
'error_count'
'output_count'
'output_percentage'
'success_percentage'
'error_percentage'
'source_agg_dq_results'
'final_agg_dq_results'
'source_query_dq_results'
'final_query_dq_results'
'row_dq_res_summary'
'row_dq_error_threshold'
'dq_status'
'dq_run_time'
'dq_rules'
'meta_dq_run_id'
'meta_dq_run_date'
'meta_dq_run_datetime'

To be able to import above mentioned statistics user should comply to the following syntax pattern:
"custom message 'dq_status': {}, 'dq_rules': {}, ..."
or
'''
custom message
'dq_status': {},
'dq_rules': {},
...
'''

Related Issue

(#87)

Motivation and Context

There was user request for providing the possibility for the user to construct custom email body and have in notifications custom statistics

How Has This Been Tested?

Tested locally with the help of local smtp debugging server

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• [x ] New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[asingamaneni]

LGTM, thanks for the contribution